Spectroscopic characteristics of doped nanoporous aluminum oxide W.M. de Azevedo a, * , D.D. de Carvalho a , H.J. Khoury b , E.A. de Vasconcelos c , E.F. da Silva Jr. c a Departamento de Quı ´mica Fundamental, Universidade Federal de Pernambuco, Cidade Universita ´ria, Recife-PE 50670-901, Brazil b Departamento de Energia Nuclear, Universidade Federal de Pernambuco, Cidade Universita ´ria, Recife-PE 50740-540, Brasil c Departamento de Fı ´sica, Universidade Federal de Pernambuco, Cidade Universita ´ria, Recife-PE 50670-901, Brazil Abstract In this work, we present photoluminescence characterization of rare earth ion doped nanoporous aluminum oxide synthesized by anodization process in different aqueous electrolyte solutions. We found that the luminescence of doped aluminum oxide strongly depends on the synthesis medium. When synthesized in inorganic acid only rare earth ions fluorescence is present, whereas nanoporous aluminum oxide synthesized in organic solvent presents two strong unexpected luminescence emission lines, one at 429 nm and the other at 491 nm, with quite long decay time when excited with long wavelength ultraviolet light. Theses results suggest that light simulation of primary colors and chromaticity control of the emitted light can be achieved by carefully doping aluminum oxide nanoporous with a combination of different rare earth ions. # 2004 Elsevier B.V. All rights reserved. Keywords: Rare earth; Nanoporous; Luminescence; Aluminum oxide 1. Introduction Nanotechnology research, to a great extend is based on fabricating functional nanoscale structures and devices in a well-controlled way, which represents one of the most difficult challenges facing today’s researchers and engi- neers. The means to organize nanoelements into device structures in order to realize their desired functionalities, using inexpensive fabrication techniques, is essential from a technological point of view. Due to the small dimensions of these nanoelements, a bottom-up self-assembly process often provides a viable approach to overcome such techno- logical challenges [1,2]. One of the important aspects of self- assembly lies in its capability of forming a large area of uniform structures through inexpensive chemical or biolo- gical processes. A major concern of using self-assembly processes to fabricate nanoscale devices for electronic or optoelectronic applications is their compatibility with high-vacuum technologies. Most electronic and optoelec- tronic devices are based on high-quality semiconductors, and their production involves complicated micro or nano- fabrication processes. Aluminum anodization [3] is one of the most controllable self-assembly processes, and nanoporous anodic aluminum oxide has been employed to synthesize a variety of nano- particles and nanowires through a template-mediated approach [4]. The electrochemical self-assembly consist of basically three steps: (a) electro polishing an aluminum foil in a suitable electrolyte to clean and prepare the surface, (b) anodizing the electropolished foil in a desired solvent with a dc current to form a porous alumina film on the surface, and finally (c) electrodepositing or chemically synthesizing the material of interest within the pores. Recently, aluminum anodization has been combined with traditional silicon processing to fabricate uniform anodic aluminium oxide thin films directly onto a silicon substrate [5], and it was also used to produce planarized microelec- tronic components from aluminum and anodic alumina layers on large scale of integration and hybrid circuits www.elsevier.com/locate/mseb Materials Science and Engineering B 112 (2004) 171–174 * Corresponding author. Tel.: +55 81 32718440; fax: +55 81 32718442. E-mail address: wma@ufpe.br (W.M. de Azevedo). 0921-5107/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2004.05.039